The present disclosure relates to communicating over access communication networks.
The current state of the art considers separately the handover procedures from the session establishment procedures, for example in 3GPP and Internet Engineering Task Force (IETF). More specifically, the handover procedures are now triggered based on a change on the physical parameters of the source access network, e.g. changes of the signal strength visible for the mobile device, or on a network initiated command. These solutions are suitable for deployment environments in which there are few access networks which overlap, which reduces the access network selection procedure to the few access networks available. In contrast, in the environments in which multiple access networks overlap largely, the physical parameters are not as important because continuity can be guaranteed by more than one access network. Instead, for handovers in these environments an important parameter for the network selection is the capacity of the access network to sustain the momentary requirements of the user of the mobile device reflected in the available resources in the specific access networks.
Currently, the session establishment procedures do not consider that the session can be established over other access networks than the access network through which the mobile device is connected to. This implies that the resource reservation procedures for the sessions are executed over the access network to which the mobile device is connected to and that the service is established only when enough resources are available to guarantee the requirements. In case that the access network cannot sustain the requirements of the session, it is released because of the missing resources.
During a session establishment procedure, the resources required by a mobile device may change. This change of the required resources implies a change in the operational costs for the operator for the specified mobile device. Sustaining the required resources over one access network has a different operational cost than sustaining the same required resources over another access network. Thus, the operator may prefer that the mobile device hands over to another access network which reduces the momentary operational costs when the specified change of the required resources happens. This case is a generalization of the case in which the sessions are released because of the missing resources, considering the operational costs of reserving resources over the access network to which the mobile device is connected to as infinite. This consideration can be made as the resources can not be reserved. The same considerations apply for a session release. In this case the momentary required resources by the mobile device decrease therefore they change.
With reference to the 3GPP Evolved Packet Core (EPC) architecture, at session establishment, the 3GPP EPC releases the session if no resources are available in the access network to which the UE (User Endpoint) is connected to. However, if an interaction between the Policy and Charging Control entities and the network selection functionality is not considered, then the architecture may release the session even when other access networks to which the UE is not connected to are available and can sustain the session. The 3GPP Evolved Packet Core (EPC) addresses the task of network discovery and handover procedures using an Access Network Discovery and Selection Function (ANDSF) which transmits policies to the mobile device. On specific conditions, the UE alone initiates the handover procedures. The policies transmitted by the ANDSF do not consider changes on the required resources of the mobile device.